Field of the Invention
The invention relates to a process and an apparatus for action control in a time slot method.
Time slot methods are used, for example, for cordless telecommunications systems based on a digital transmission technique. Those telecommunications systems use Time Division Multiple Access (TDMA) as access to the spectrum. The invention can be applied, for example to the DECT (Digital Enhanced Cordless Telecommunications) Standard.
A TDMA time slot method radio system requires timers to control the timing of actions in individual time slots. Those timers are also called counters or bit counters in the following text. They may be used for bit, time slot, frame and multi-frame synchronization and time.
The PMB 2727 DECT Multichannel Burst Mode Controller ("MBMC") is known from the prior art. That module includes only the functionality of a base station. The PMB 2727 includes a bit counter for the transmitting phase (=TX bit counter) and a bit counter for the receiving phase (=RX bit counter). The time sequence of the first 12 transmitting time slots is governed by the TX bit counter, and that of the second 12 receiving time slots by the RX bit counter. However, in that case, the receiving phase is always subject to the problem of it being possible for a time slot which is received too late to collide with the next time slot which, under some circumstances, is received early. That collision does not just occur because of the guard space between two receiving time slots being used up by the distance between the mobile parts, but as a result of the fact that receiving time slots have to be provided even before reception, by locking on the receiver.
In the case of DECT, the guard space bit width includes 56 bits. Of those, 12 bits are lost because of the preparatory task for the second receiving time slot, being used to switch on the receiver. Final tasks relating to the preceding time slot last until about bit No. 436. Thus, 480-436-12=32 bits remain for the distance between the mobile part and the base station. However, an optimum base station should be able to use the possible 56 bits in the guard space duration without being limited by the implementation in baseband. In the case of a repeater, the method which is known from the PMB 2727 can be implemented only with a very high level of complexity and with a high risk level in terms of functionality.